What the best way to temporary mount a battery? Just need to mount it for a couple of trial runs (we are not close to deciding the final battery position).
We used some aluminum angle to support the base, tied it down with string, and added a pool noodle section to (try to) keep it from moving. Before the string, we’d tried duct tape and the battery went flying.
Ziptied surgical tubing bands or bungee tiedown work well.
Not knowing what your robot looks like in the area you intend to mount it, there’s really no way to say what would work well. You need to check all 29 directions it could move to make sure it can’t move that way. 26 directions are translations:
- toward each of the 6 faces of the battery
- toward each of the 8 corners
- toward each of the 12 edges
And the other three are rotations: roll, pitch, yaw.
If you’re using the KoP chassis and have enough room inside, a battery fits snugly inside the front or rear plate. That will knock out roll, pitch, and five more directions by itself, and give support for several of the others.
29 degrees of freedom is ridiculous - for example, there is no way you can secure all 6 faces of the battery OR all 8 corners while leaving an edge free to translate. In reality, as with all solid objects in 3D space, there are 6 degrees of freedom - translation in X / Y / Z and roll / pitch / yaw. If your battery is fully constrained in all 6 of these degrees of freedom, it can’t move regardless of whether or not you can see a corner of the battery.
As to answer the OP’s question - you basically want to secure the battery as well as you would secure it on the final robot, even temporarily, since you’re likely to be flying across obstacles and whatnot. Some aluminum angle on four sides with a strap across the top is an easy temporary way to do it. Don’t use tape. Try to take advantage of existing geometry on your robot (ie the side of the chassis, etc) if you can. Do secure the top of the battery as you’ll be jumping over some rough obstacles and it could jostle loose.
Large zipties, one of the AndyMark battery mounting kits, or a tie-down kit will work for temporary mounting purposes.
But make sure temporary doesn’t turn into permanent. Like Chris said, start designing a permanent solution to take use of existing robot geometry. You don’t want to go out on the field and have your season ruined by a loose battery
I’m unsure what you’re trying to get at. There are 6 degrees of freedom for any given object. Translation in X, Y, and Z. Rotation in X, Y, and Z. Whether you’re talking about a battery, wheel, shaft, gear, arm, etc. those are what you need to think about.
For your battery, if you were to screw together a rectangular wooden frame that the battery lies in, you would take care of translation in X and Y, and rotation in Z. Large zip ties or a nice Velcro strap and you can hold it down to eliminate translation in Z, and rotation in X and Y. Just an example.
At risk of piling on, here’s an excerpt from an email I wrote to my team once.
To better understand “degrees of freedom,” consider a fish flying through the air:
The fish is free to translate along each of the three principal axes of our 3-D world: X, Y, and Z. That’s 3 DOFs. The fish is also free to rotate about each of these axes as well. That’s another 3 DOFs, for 6 total. All solid objects floating through space, like the fish is doing, have exactly 6 degrees of freedom.
Secure your battery well, or it will fly like a fish.
It takes time, but in order to do this construct a frame that secures the battery and then secure it to the frame with bolts.
It doesn’t matter the materials you build the battery restraint from (wood, steel, aluminum, polycarb, etc.) - it is a VERY bad idea to place the battery without it being constrained. You do not want the battery to come loose for obvious reasons: damage to the battery (costly and messy), and damage to your robot.
Build a battery frame that you can use now and in subsequent years. Take the time now and save time later.
We made a frame in the middle of our chassis out of angle aluminum for testing, and then used one of these to anchor the battery down with Velcro. It worked quite well, and I would say that for testing the battery base is probably unnecessary.
Whatever you do, don’t let this happen:
Students got a little bit too excited about a new drive maneuver they discovered…
We have stockpiled a few of these over the years. They work very well for temporary or permanent mounts.
While there are only six actual degrees of freedom, looking only at motion directly along each one is not enough. You need to consider all of the diagonal possibilities as well. I recall seeing a documentary about a building in NYC that had some cantilevered sections. Engineers wind-tunnel tested models for north, south, east, and west winds. It passed, and was built. After it was built, it behaved as expected in north, south, east, and west winds. When the first nor’easter blew in, the building swayed dangerously, and they had to retrofit structure into a working office building by night to prevent a “domino effect” of falling buildings. When it comes to safety, consider the “in between” cases.
That definitely would ruin your season. The blue box of G1 says you can’t drag your battery or you won’t pass inspection.
Remember that the battery is a 8lb box of acid, death and lead. When in doubt mount it more solidly then you think you need.
Gaffers tape, lots and lots of gaffers tape
Why wouldn’t you trust the AM battery mount kit as a permanent solution?
We ordered ours without Death…
How much you have to do to secure it depends on the frame you are using. Also what do you mean by a “few runs”. If you are running around on the flat floor, some zip ties would probably be fine (we have some really thick ones), but if you are going over/through obstacles you might need more. Also, do you have anything really solid to attach to, etc.
If you have a kit chassis you have scrap pieces from it. Those scrap pieces happen to fit perfectly on a battery. So, cut 1 of them in half and bolt it to your frame. Get a Velcro strap and bam Permanent Battery holder in 5 minutes.
I do not see a point to a temporary battery holder.
That is a very expensive battery mount.